Under Third Generation Partnership Project (3GPP) standards, a WTRU is required to monitor cells on other frequencies and on other modes and radio access technologies that are supported by the WTRU. In order to allow the WTRU to perform measurements, a network commands the WTRU to enter into compressed mode.
During transmission gaps in the compressed mode, physical data bits for the dedicated physical channels (DPCHs) are lost. However, the transport data can typically be recovered by several mechanisms: 1) interleaving across multiple frames, 2) error correction coding, and 3) mechanisms built into the standards to offset the degradation caused by lost channel bits (e.g. spreading factor (SF) reduction, puncturing, and power control in the compressed mode).
Transmission gaps in the compressed mode affect not only DPCH transmissions but also HSDPA transmissions. However, currently there is no mechanism for performance recovery of HSDPA transmissions that overlap with compressed mode transmission gaps. There is no coordination of the compressed mode transmission gap scheduling and HSDPA packet scheduling in current wireless communication standards. HSDPA packet scheduling that is done without considering the impact of compressed mode transmission gaps will result in wasted resources and diminished system capacity.